There used to be sites that would do this diffing on news-sites, I even tried building one at some point. The idea was to reduce the memory-hole effect that the

There used to be sites that would do this diffing on news-sites, I even tried building one at some point. The idea was to reduce the memory-hole effect that the web infrastructure has produced and promoted. I remember Mark Pilgrim at one point targeting Dave Winer with something like that, as they were feuding and Winer is/was known for rewriting his blogposts.